The third generation wide band gap semiconductor materials represented by silicon carbide have many outstanding advantages, such as wide band gap, high breakdown electric field, high electron saturation drift speed, corrosion resistance and irradiation resistance. It has important applications in the fabrication of high-efficiency ultraviolet detectors, gas sensors, friendly biosensors, and high-frequency, high-power, anti-radiation and other electronic devices.
In particular, silicon carbide has a band gap of 3.2 eV, a breakdown electric field of 3.0×106 V/cm, an ionization energy of 7.78 eV, a resistivity of 1012Ω.cm, a melting point of 2700° C. and an electron saturation velocity of 2.0×107 cm/s. It is an ideal material for developing semiconductor radiation detectors.
Several methods have been mastered for preparing silicon carbide single crystals. The conductive properties of n-type and p-type silicon carbide can be achieved by ion implantation. Semi-insulating silicon carbide can be prepared by doping vanadium during the growth process. According to the reported research results, silicon carbide materials are mainly used to prepare power electronic devices and photoelectric devices.
At present, silicon carbide related X-ray detectors with higher performance requirements (the dark current and carrier transmission loss should be as small as possible) are mainly fabricated by homogeneous epitaxy methods.
Due to the limitation of the existing technical conditions, the thickness of the detection sensitive zone of the silicon carbide X-ray detector, which is prepared by the epitaxy growth method, will not exceed 150 microns. For the X-ray has strong penetration, this thickness cannot make the high energy X-ray deposit sufficiently. It directly affects the X-ray detection sensitivity, detection efficiency and the energy resolution, or directly lead to the inability to detect high-energy X-ray.
However, compared with the structure of epitaxy grown silicon carbide devices, the advantages of using silicon carbide single crystal to develop X-ray detectors are as follows: 1. the thickness of single crystal can be cut to meet the needs of high-energy X-ray detection; 2. the high quality of single crystal is conducive to the carrier's effective collection. To this end, the invention proposes using silicon carbide single crystal for the development of X-ray detectors.